Cyclobutane derivatives containing polyunsaturated substituents and their preparation



United States Patent 3,363,011 CYCLOBUTANE DERIVATIVES CONTAINING POLYUNSATURATED SUBSTITUENTS AND THEIR PREPARATION Harris D. Hartzler, Wilmington, DeL, assignor to E. I. du Pont de Nemours and Company, Wihnington, Del., a corporation of Delaware No Drawing. Filed Sept. 10, 1964, Ser. No. 395,568 Claims. (Cl. 260-648) ABSTRACT OF THE DISCLOSURE Selected unsaturated derivatives of cyclobutane and their preparation by addition reactions of cumulenes.

Summary and details of the invention This invention relates to, and has as its principal objects provision of, certain polyunsaturated derivatives of four-carbon ring compounds and methods for preparing the same.

PRODUCTS The products of this invention are compounds of Formulas 1, 2, and 3:

(1) R R C=C=CC=C=OR R x x o-r zxeo R1R2C=C=C-O= =CR3R aliphatic unsaturation; the Xs are the same or different and are hydrogen, fluorine, alkyl, or fiuoroalkyl (including monofiuoroalkyl and polyfluoroalky-l); and the Ys are the same or different and are hydrogen, alkyl, or perfluoroalkyl.

'For reasons of availability, preferred products within the scope defined above are those in which the carbon content of the R groups attached to any one carbon is at most 14. Especially preferred products are those in which all the Rs are the same and are hydrocarbyl .groups free of aliphatic unsaturation and of at most seven carbons. Equally especially preferred products are those in which the R groups are bonded through carbon bearing no hydrogen.

Because of availability of starting materials, preferred products of Formula 1 are those in which the X Xd -dX X group contains at most seven carbons. For the same reason, products of Formula 1 comprising another preferred class are those in which the groups are divalent hydrocarbyl'or divalent iluorocarbyl.

Especially preferred products of Formula 1 are those in which each X is fluorine.

For the same reason, preferred values of Y are hydrogen, lower alkyl, and lower perfiuoroalkyl, particularly lower perfluoroalkyl.

BEST AVAILABLE COPY Patented Jan. 9, 1968 It will be evident that in appropriate cases of asymmetrical substitution, some of the present novel compounds can exist as geometrical isomers. Such isomeric forms are included within the invention.

PROCESSES The products are prepared by cycloaddition reactions of the corresponding tetrahydrocarbylhexapentaenes,

where the Rs are as defined above, with an ethylenically unsaturated compound of the formula X X C=CX X of up to seven carbons, where the Xs are as defined above. This process is illustrated in Example 1.

Process H.Products of Formula 2 are prepared by heating a tetrahydrocarbylhexapentaene of Formula 4 in the absence of a coreactant. In this process, two molecules of the cumulene undergo cycloadditive dimerization, or cyclodimerization, as illustrated in Example 2.

Process III.-Products of Formula 3 are prepared by reacting a tetrahydrocarbylhexapentaene of Formula 4 with an acetylenic coreactant of the formula YICECY2, where Y and Y are as defined above.

All three processes can be carried out at temperatures between about 50 C. and the decomposition temperatures of the products. Temperatures of about ISO-250 C. are preferred. An inert solvent can be used in each process but is not required.

The processes can all be carried out at subatmospheric, atmospheric, or superatmospheric pressures. Process II is conveniently run at atmospheric pressure. Since most of the ethylenic and acetylenic reactants used in Processes I and III boil below the preferred temperatures at which the processes are carried out, it is convenient to run these processes at the autogenous pressures of closed systems. The yields in these two processes can be increased by increasing the pressure, especially when the ethylenic or acetylenic reactant is a gas under ordinary conditions. For ethylenic reactants in particular, pressures as high as several thousand atmospheres can be used to advantage, with rcpressuring of the ethylenic reactant if desired.

In Processes I and III, the mole ratio of reactants is not critical. Usually the ethylenic or acetylenic coreactant will be both more readily available and more easily removed from the final product mixture than the ciunulene reactant; it is convenient, therefore, to use a considerable excess of the former to insure complete consumption of the latter. Coreactant/cumulene mole ratios as high as 50/1 are advantageously used, particularly when the coreactant is a gas under ordinary conditions.

PROPERTIES The products of the invention are well-defined crystalline solids, stable to air and Water at ordinary temperatures. They can be isolated and purified by recrystallization from common organic solvents or by sublimation.

The tetrahydrocarbylhexapentaenes used as starting materials are members of a known class of compounds. See, for example, Cadiot et a1., Bull. Soc. Chim. France, 1961, 2176. They can be prepared by coupling reactions of the corresponding dihydrocarbylethynylcarbinols, which are in turn made from ketones and acetylene. Specifically, the preparations of diphenylethynylcarbinol and tetraphenyl hexapentaene from benzophenone are described by BEST AVAILABLE COPY a Hartzler, J. Am. Chem. Soc., 83, 4990 (19 61). Tetra-tbutylhexapentaene, used in Examples 1, 2, and 3, can be prepared by the same method from di-t-butyl ketone. Unsymmetrical tetrahydroearbylhexapentaenes of Formula 4,

in which the R entities at the ends of the carbon chain are KCH3)3C],O=C=C C=C=C[C(CHMa different, are prepared by the same type of coupling reaction of two different dihydrocarbylethynylcarbinols. b l [(GH3)3C]2(3=3C=CC=C=hC[C(:HM Tetra-tuty hexapentaene 0 g.) was eate in a EXAMPLES glass reactor at 200 C. and atmospheric pressure for 15 The following nonliniiting examples illustrate the prodminutes. The mixture was cooled, excess pent'ane was ucts of this invention. added, and the resulting suspension was filtered to give 0.27 g. (90%) of solid tetrakis-(di-t-butylvinylidene)cyclo- Example ij g i gif zg gz gg butane, M.P. 350360 C. Recrystallization from xylene gave colorless crystals that melted at 361 C. without de- [(CH3)3C]2C=C=C=C=C=C[C(CH3)3]2 composition Analysis.-Calcd. for C H C, 87.9; H, 12.1; M.W., CF1=CFfl 601. Found: 0, 88.0; H, 12.0; M.W., 59s (ebull. in bena)sC]2C=C=CC=C= l 1110312 FgC-CF; The molecular-weight determination was carried out on A tubular glass reactor was charged with 0.92 g. of sepafate sample PrePaIed as described above tetra-t-butylhexapentaene and 20 ml. of benzene, cooled The mfrafed aibsorpnon spectrum f the Product in liquid nitrogen evacuated, charged additianany with sium bromide disk) showed absorption characteristic of 7.3 g. of tetrafluoroethylene, and sealed. The reactor was Qtumted H t 3-37,u, 3.43,u, and 3.4%, and absorpthen heated at C and autcgenous Pressure for Six tion characteristic of al lenic C=C at 5.12 and 5.l9 No hours, cooled, and opened. Volatile materials were re- 5 absorption characte istic of any other kind of carbon-carmoved by evaporation, and the solid residue was crystalhon unsaturatlon was Present The proton spectrum Zed from methanol to give 093 (70%) of 1,2 bis(di of the product showed one sharp resonance at 7:8.80. t buty1viny1idene) 33,434 tetrafluorocyclobutane, MB The ultraviolet absorption spectrum of the product in 1284300 C. A Second recrystallization from methanol tetrahydrofuran solution showed absorption at 3.1 6 m gave aproduct melting at 129.5l30.5 C. u (E=1720), 2.68 m (E=13,200),

Analysis.Calcd. for C H F c, 72.0; H, 9.06; F, 258 ($16,300) and 250 me ($15,800)- Found; C 719; H, 895; F, 18.8; C, 722; H, 838; Any of the tetrahydrocarbylhexapentaenes of the first F 181 column of Table I or the first column of Table II can be The infrared absorption spectrum of the product (potascyclodlmerized by P of P Q 2 to gwe the Sium bromide disk) Showed absorption Characteristic of corresponding tetrakis(dihydrocarbylvinylidene)cyclobusaturated C-H, saturated CF, and allenic C=C. There tanes' was no absorption characteristic of any other kind of car- Example 3,3,4-bis(di-t-butylvinylidene)-1,2-bisblon-carbon unsaturation. The fluorine (F n-m-r (nu- (trifluoromethyl)cyclobulene c ear-magnetic-resonance) spectrum showed only one sharp resonance, which was +2520 c.p.s. from 1,2-di- [(CH3)EC]2C C CTFC C O[C(OHM: fluoro-l,1,2,2-tetrachloroethane at 56.4 me. The hydrogen CFBGZCCFa n-m-r spectrum showed one sharp resonance at 7:8.7 6.

By essentially the procedure of Example 1, with routine [(OH3)3C]2C CHC C C-C[C (Cnmh modifications as necessary, other tetrahydrooarbylhexa- =CCF pentaenes can be reacted with ethylenically unsaturated A tubular glass reactor was charged with 0.49 g. of compounds to give products of the invention of Formula tetra-t-butylhexapentaene and 7 ml. of benzene, cooled 1. Some of these reactants and products are shown in the with solid carbon dioxide, exacuated, charged additionally following table. with 10 g. of hexafluoro-Z-butyne, and sealed. The re- TABLE I Tetraliydrocarbylhexapentaene Ethylenic Coreactant Substituted Cyclobutane actor was heated at 200 C. and autog'enous pressure for four hours, cooled, and opened. Volatile materials were removed by evaporation, and the residual solid was crystallized from ethyl alcohol to give 0.34 g. (ca. 45%) BEST AVAILABLE COPY The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A compound of the group consisting of of crude 3,4-bis-(di-t-butylvinylidene)-1,2-bis(trifluoro- 5 (1) R R C=C=C-C= =CR'R methy1)cyclobutene, M.P. 1l6140 C. The product was purified by sublimation at about 130 C./0.4 mm. to give colorless crystals, M.P. 1355-137 C. R R C=C=CC=C=OR=R 'Analysis.Calcd. for C H F C, 67.5; H, 7.85; F, 24.7. Found: C, 67.1; H, 7.92; F, 25.1. 10 and The infra-red absorption spectrum of the product (potassium bromide disk) was in complete agreement (3) with the structure of the product in the above equation. Y1C= Yz It showed absorption at 3.39 1,, 3.40 and 3.45;; (saturated w C-H); 5.05 1. and 5.10;. (allenic C C); 6.07; (cyclo- Wherem: butene 01 3); d 725,, [(CH3)3C The ultraviolet the lts, in which any unsaturation is aromatic and absorption spectrum of this product in isooctane solution Whlch are aitaehed to the depleted carbons through Amx. 7 Imy (6=11100) carbon bearing no hydrogen, are monovalent hydro- By essentially the method of Example 3, the tetrahydrocafbyl in the ease of bonded to one Carbon, carbylhexapentaenes and acetylenic compounds shown in divalent hydrocarbyl, the two Rs bonded to any one Table II can be reacted to form products of the invention. depicted carbon having a total of up to 14 carbons;

TABLE II Tetrahydrocarbylhexapentaene Acetylem'o Coreaotant Substituted Cyclobutane i=C=C=C=C=j CHECH C=C=CC=C=j l (oCHaC H )zC=C-=C=C=C=C(GaHs): CF3G5CCH3 (OCH3CQH4)IC=C=CC=C=C(C5116)! 13E: CH3 CE; CH; CH: CH: CH: CH; CHr-C /C-CH: OHr-C\ O-CH:

c=o=c=o=c=o 01130 004119 I o=o=o-c=o=o i H1-C C-CH; CH:C CHaC=CC Hn C H:

C: CH: 03 CH: Ca CH: C: CH;

UTILITY the Xs are selected from the group consisting of As shown by the following example, the products of the invention are generically useful as inhibitors of freeradical-initiated addition polymerization.

Example A Two identical solutions were prepared, each containing 10 ml. of acrylonitrile, ml. of benzene, and 0.05 g. of azobisisobutyronitrile. To one solution was added 0.10 g. of tetrakis(di-t-butylvinylidene)cyclobutane. The two solutions were heated at 60-70" C. with stirring in an atmosphere of nitrogen. The following observations were made on the two solutions:

Time Solution Containing Tetra- Other Solution (hrs.:min.) kls(di-t-butylvinylidene)- (Control) cyclobutane 0:00 Heating at 60-70 0. Same.

started. I

0:30 No change Solid polyaerylonitrile separating.

1:25 Solution slightly hazy; Reactor filled with solid polyacrylonitrile polymer. starting to separate.

These observations show that the tetrakis(di-t-buty1- vinylidene)cycl-obutane strongly inhibited the free-radicalinitiated polymerization of acrylonitrile.

Since obvious modifications and equivalents in the example will be evident to those skilled in the chemical arts, I proposed to be bound solely by the appended claims.

hydrogen, fluorine, alkyl, and fiuoralkyl, the

the Rs being as in claim 1.

6. The process of producing a compound of Formula 2 of claim 1 which comprises heating, at a temperature between about 50 C. and about 250 C.,

a compound of the formula with a compound of the formula X X C=CX X of up to 7 carbons, the Rs and Xs being as in claim 1.

BEST AVAILABLE COPY 7. The process of producing a compound of Formula 3 of claim 1 which comprises heating, at a temperature between about 50 C. and about 250 C.,

a compound of the formula with a compound of the formula Y C CY the Rs and Ys being as in claim 1.

8. The process of producing the compound of claim 3 which comprises heating, at a temperature between about 50 C. and about 250 C., tetra-t-butylhexapentaene.

9. The process of producing the compound of claim 2v which comprises heating, at a temperature between about 8 10. The process of producing the compound of claim 4 which comprises heating, at a temperature between about 50 C. and about 250 C., tetra-t-butylhexapentaene wit-h heXafluoro-t-butyne.

References Cited Uhler et al.: I. Am. Chem. Soc., vol. 84, p. 3397 (1962).

Adams et a1.: Organic Reactions, pp. 2, 34 to 36, 40, 43,

10 and 47 (1962).

LEON ZITVER, Primary Examiner.

DANIEL D. HORWITZ, Examiner.

50 C. and about 250 C. tetra-t-butylhexapentaene with 15 M. JACOB, Assistant Examiner.

tetrafluoroethylene.

BEST AVAILABLE copy UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,363,011 January 9, 1968 Harris D. Hartzler It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6 line 46 for "fluoralkyl read fluor0alky1,-- LineTQS, for "Formula 2" read formula 1 Signed and sealed this 29th day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

